980 resultados para Hydrobiology and pollution


Relevância:

80.00% 80.00%

Publicador:

Resumo:

L’eau a longtemps été considérée comme une ressource commune non susceptible d’appropriation et accessible à tous. De nos jours, toutefois, face à l’inégale répartition de l’eau sur la planète, à l’augmentation constante de la population et à la multiplication des usages qui entraînent la surexploitation et la pollution des ressources hydriques, l’eau prend une valeur nouvelle. L’eau devient de plus en plus un enjeu stratégique, politique et commercial. En conséquence, la redéfinition du statut juridique de l’eau devient un objet de débat important. Ce débat est avant tout un débat rhétorique et une « bataille » idéologique entre des groupes qui soutiennent différentes approches et qui cherchent à obtenir le monopole de la nouvelle réalité et créer ainsi le nouveau droit. Deux grandes approches s’affrontent pour redéfinir la ressource. La première, celle qui envisage l’eau comme un bien économique, soutient que pour éviter les problèmes de gaspillage et de pollution, l’eau doit être soumise aux lois de l’offre et de la demande. La deuxième, celle qui considère l’eau comme une chose commune, non appropriable et hors commerce, soutient que la valeur d’une ressource aussi vitale que l’eau ne peut être établie par les lois du marché puisque cette alternative ne permet pas d’assurer l’accès à l’eau aux plus démunis de la société. Cette approche prône également la reconnaissance d’un droit humain à l’eau. Notre thèse tente de déterminer comment s’effectue le choix du statut juridique de l’eau, et ce, tant au Québec qu’au Mexique. Notre question de recherche est traitée selon une perspective constructiviste en vertu de laquelle le statut juridique de l’eau serait une réalité « construite » et le nouveau droit serait le résultat des luttes, des oppositions et des compromis entre les acteurs sociaux impliqués. Notre terrain d’étude est le Québec et le Mexique. En effet, ce sont des territoires intégrés économiquement par le biais de l’ALENA où l’on observe des variations importantes en termes de ressources, de prélèvements et de consommation. Au Québec, nous analysons le débat qui a eu lieu lors de la Consultation sur la gestion de l’eau au Québec (1999), notamment les discours concernant le statut de l’eau, la gestion publique/privée des services d’eau et l’exportation en vrac de la ressource. Au Mexique, nous analysons les représentations des acteurs sociaux à l’occasion de l’adoption de la Loi des eaux nationales de 1992, notamment les questions qui comportent un lien étroit avec la symbolique de l’eau. Or, nous avons remarqué que le résultat de ces constructions sociales au sein de ces territoires est complètement différent. Au Québec, on a confirmé le statut de l’eau en tant que chose commune, tandis qu’au Mexique, c’est plutôt la symbolique de l’eau en tant que bien économique qui a été adoptée dans la nouvelle législation portant sur l’eau.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

In the early 19th century, industrial revolution was fuelled mainly by the development of machine based manufacturing and the increased use of coal. Later on, the focal point shifted to oil, thanks to the mass-production technology, ease of transport/storage and also the (less) environmental issues in comparison with the coal!! By the dawn of 21st century, due to the depletion of oil reserves and pollution resulting from heavy usage of oil the demand for clean energy was on the rising edge. This ever growing demand has propelled research on photovoltaics which has emerged successful and is currently being looked up to as the only solace for meeting our present day energy requirements. The proven PV technology on commercial scale is based on silicon but the recent boom in the demand for photovoltaic modules has in turn created a shortage in supply of silicon. Also the technology is still not accessible to common man. This has onset the research and development work on moderately efficient, eco-friendly and low cost photovoltaic devices (solar cells). Thin film photovoltaic modules have made a breakthrough entry in the PV market on these grounds. Thin films have the potential to revolutionize the present cost structure of solar cells by eliminating the use of the expensive silicon wafers that alone accounts for above 50% of total module manufacturing cost.Well developed thin film photovoltaic technologies are based on amorphous silicon, CdTe and CuInSe2. However the cell fabrication process using amorphous silicon requires handling of very toxic gases (like phosphene, silane and borane) and costly technologies for cell fabrication. In the case of other materials too, there are difficulties like maintaining stoichiometry (especially in large area films), alleged environmental hazards and high cost of indium. Hence there is an urgent need for the development of materials that are easy to prepare, eco-friendly and available in abundance. The work presented in this thesis is an attempt towards the development of a cost-effective, eco-friendly material for thin film solar cells using simple economically viable technique. Sn-based window and absorber layers deposited using Chemical Spray Pyrolysis (CSP) technique have been chosen for the purpose

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Este trabajo contribuye al análisis de la incidencia del paradigma del Desarrollo Urbano Sostenible en el proceso de toma de decisiones legislativas en Colombia, concentrándose en la discusión y definición de la agenda legislativa sobre asuntos urbanos, durante el periodo 1991-2006.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

La pobreza, la mala nutrición, la injusticia social y ambiental predominan en América Latina como factores que condicionan la acción de sustancias contaminantes sobre los niños. La intoxicación con plomo y la contaminación ambiental constituyen problemas de salud pública en todo el mundo, afectando múltiples sistemas del organismo, en especial los sistemas nervioso central (SNC), hematopoyético, renal, endocrino y óseo, entre otros, en las primeras etapas de la vida. Objetivo: evaluar los efectos clínicos, bioquímicos y vasculares en niños expuestos a fuente conocida de plomo. Materiales y métodos: se estudiaron siete niños con fuente definida de exposición a plomo y se realizó laboratorio general y específico para plomo. Se valoraron función endotelial y parámetros electrocardiográficos. Estadística descriptiva. Resultados: media de edad: 6,2 años (DE± 1,6), hematocrito promedio 31% (DE±0,02); hemoglobina promedio 10,2 gr/dl (DE± 0,78). La totalidad de las muestras, 100%, presentó anemia, hipocromía, microcitosis y anisocitosis marcadas. Plombemia promedio: 37,9 ug/dl (DE± 6,22), ALA-D promedio: 8,9 U/L (DE±4,5). No se encontraron modificaciones en el perfil lipídico ni en función renal. Todos presentaron microalbuminuria y disfunción endotelial. Conclusión: estos resultados evidencian los efectos que la exposición ambiental al plomo puede producir en niños no expuestos laboralmente.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Extractability of Cd. Cr, Cu, Ni, Pb, and Zn in a dredged sediment disposal site was assessed using single extraction Procedures (H2O; 0.01 M CaCl2; 1 M NH4OAc NH4OAc-EDTA. CaCl2-TEA-DTPA). Only Cd and Zn were Found to exceed statutory threshold values for total content. The field was planted with Salix viminalis "Orm" and accumulation of heavy metals in bark, leaves, roots, and wood was evaluated at seven sampling locations along an observed gradient in texture and pollution. Biomass production was high, ranging from 13.2 to 17.8 t ha(1) y(1) dry weight. Metal accumulation in aboveground Plant parts Was low. amounting to the following annually extracted mass or metals per ha: 5034 g Zn, 83 g Cd. W g Cu. 83 g Pb, 12 g Ni and 6 g Cr. The use of accumulating clones and the use of soil amendments might enhance extraction efficiency in future research. (C) 2005 Elsevier Ltd. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Accurate monitoring of degradation levels in soils is essential in order to understand and achieve complete degradation of petroleum hydrocarbons in contaminated soils. We aimed to develop the use of multivariate methods for the monitoring of biodegradation of diesel in soils and to determine if diesel contaminated soils could be remediated to a chemical composition similar to that of an uncontaminated soil. An incubation experiment was set up with three contrasting soil types. Each soil was exposed to diesel at varying stages of degradation and then analysed for key hydrocarbons throughout 161 days of incubation. Hydrocarbon distributions were analysed by Principal Coordinate Analysis and similar samples grouped by cluster analysis. Variation and differences between samples were determined using permutational multivariate analysis of variance. It was found that all soils followed trajectories approaching the chemical composition of the unpolluted soil. Some contaminated soils were no longer significantly different to that of uncontaminated soil after 161 days of incubation. The use of cluster analysis allows the assignment of a percentage chemical similarity of a diesel contaminated soil to an uncontaminated soil sample. This will aid in the monitoring of hydrocarbon contaminated sites and the establishment of potential endpoints for successful remediation.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

New models for estimating bioaccumulation of persistent organic pollutants in the agricultural food chain were developed using recent improvements to plant uptake and cattle transfer models. One model named AgriSim was based on K OW regressions of bioaccumulation in plants and cattle, while the other was a steady-state mechanistic model, AgriCom. The two developed models and European Union System for the Evaluation of Substances (EUSES), as a benchmark, were applied to four reported food chain (soil/air-grass-cow-milk) scenarios to evaluate the performance of each model simulation against the observed data. The four scenarios considered were as follows: (1) polluted soil and air, (2) polluted soil, (3) highly polluted soil surface and polluted subsurface and (4) polluted soil and air at different mountain elevations. AgriCom reproduced observed milk bioaccumulation well for all four scenarios, as did AgriSim for scenarios 1 and 2, but EUSES only did this for scenario 1. The main causes of the deviation for EUSES and AgriSim were the lack of the soil-air-plant pathway and the ambient air-plant pathway, respectively. Based on the results, it is recommended that soil-air-plant and ambient air-plant pathway should be calculated separately and the K OW regression of transfer factor to milk used in EUSES be avoided. AgriCom satisfied the recommendations that led to the low residual errors between the simulated and the observed bioaccumulation in agricultural food chain for the four scenarios considered. It is therefore recommended that this model should be incorporated into regulatory exposure assessment tools. The model uncertainty of the three models should be noted since the simulated concentration in milk from 5th to 95th percentile of the uncertainty analysis often varied over two orders of magnitude. Using a measured value of soil organic carbon content was effective to reduce this uncertainty by one order of magnitude.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Owing to na intense process of urban development, urban uneasiness and discomfort in the daily life of populations have nowadays, especially in the big cities, become increasingly ordinary issues. Population density, degeneration of central areas and pollution are some of the environmental stressors the urban man is subjected to. The existence of open areas in the urban network contributes to a better movement of the air and transforms salubrity conditions. Yet, it has been noticed that parks and squares are disappearing from the heart of the city districts. In their place there are either unused plots of land where garbage has been dumped or nearly all-paved squares with meager or no vegetation at all. Such areas, when handled properly, play an important role in the city because in addition to being zones for rendering a mild climate they perform social, cultural and hygienic functions. Aiming at demonstrating that proper handling of green areas can favorably influence the local microclimate, we have attempted to develop analysis from the point of view of bioclimatizing attributes of urban form and their relationship to the local microclimate found in the eight open areas located in the Ponta Negra Housing Complex in the city of Natal/RN

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This present dissertation has as its aim of study an analysis of the environmental policy and the urban development at the Periperi Hill. Such analysis arose due to concerns related to the disordered occupation in that Hill and also due to the environmental problems caused by this occupation. By opening roads and developing areas for housing and mineral extraction activities, man has altered considerably the landscape natural balance in that hill and caused among other difficulties, grave environmental problems, such as the erosin at the hill coast, deforestation, obstruction and pollution of the Verruga River. Therefore, in 1998 it was decreed by the Municipal Public Power that Periperi Hill became an Environmental Preservation Area with a Unit of Conservation known as Periperi Hill Municipal Park, an environmental policy implemented at the Hill that aims to hinder this occupation and to protect areas that are of great environmental importance to the city. It looking at what is now exposed and aiming to consider the Periperi Hill s environmental policy and the relationship of the occupation process, that this present work has the objective of understanding how the expansion of the city s urban network in Vitória da Conquista BA and the mineral activities cause an influence in the process of environmental degradation at the Periperi Hill

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The fishing is made possible by the handiwork of a fisherman, not using appliances that achieve the same levels of industrial fishing productivity and not causing environmental impacts on fish stocks with the same intensity. The adoption of sustainability practices in this type of fishing has been requested for the achievement of environmental and socioeconomic improvements, since its production has been decreasing over the years and overfishing has led to reduced stocks also stand out environmental aggressions such as pollution. Thus, this research aims to analyze the interference of environmental aspects/impacts that permeate the activity performed by fisherman on the beach of Ponta Negra, Natal-RN, in order to propose recommendations for environmental sustainability. We used a methodology based on the ergonomic work analysis (WISNER, 1987; GUERIN, 2001; VIDAL, 2008) using techniques such as observational and interactional observation protocols, photographs, videos, conversational action, and listening to verbalizations. To understand the vulnerability of the environment in which the activity is carried fisherman and the interferences that it suffers, we used the study of environmental aspects/impacts (SÁNCHEZ 2008). As a result, it appears that from the observations located and reports raftsmen, changes in the sea, the search for new fishing grounds farther from the coast, reducing fishery production, waste generation and pollution of the workplace, and the difficulty in docking rafts, factors arising from the pressures both for society as Seen by fisherman, denoting the necessity of drawing up recommendations and actions proposed by management activity by promoting discussion among raftsmen and accountable institutions, and training through workshops on environmental education, aiming to positive changes in the activity fisherman from Ponta Negra and the environment in which raftsmen are inserted in order to seek a sustainable activity, preserving its characteristics

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The large use of plastics has generated a waste deposit problem. Today plastic wastes represent 20% in volume of the total waste in the municipal landfills. To solve the disposal problem of plastics methods have been employed such as incineration, recycling, landfill disposal, biodegradation and the use of biodegradable polymers. Incineration of plastic wastes provokes pollution due to the production of poisonous gases. Recycling is important to reduce final costs of plastic materials, but is not enough in face of the amount of discarded plastic. In landfills plastic wastes remain undegraded for a long time, causing space and pollution problems. Biodegradation is a feasible method to treat some plastics, but intensive research is necessary to find conditions for the action of microorganisms. All of these methods are important and the practical application of each one depends on the type and amount of the plastic wastes and the environmental conditions. Therefore, a great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Realizou-se um estudo caso-controle com o propósito de se detectar possíveis fatores de risco para o aparecimento de fissuras orais. Foram objeto de análise: local de moradia da mãe nos quatro primeiros meses de gestação, poluição, aplicação de pesticida/herbicida na lavoura, doenças dos pais, doenças da mãe nos quatro primeiros meses de gestação, ingestão medicamentosa nesse período, hereditariedade, tabagismo, consumo de bebida alcoólica e exposição a raio-X. Foram aplicados formulários às mães referentes aos 450 casos, sendo 354 portadores de fissuras labiais ou lábio-palatais e 96 de fissuras palatinas, e às mães referentes aos 450 controles. Empregou-se análise multivariada e as variáveis hereditariedade (RR=4,96), epilepsia na mãe (RR=2,39) e ingestão de anti-inflamatório (RR=2,59) foram consideradas fatores de risco para fissuras labiais ou lábio-palatais. As variáveis hereditariedade (RR=2,82) e poluição (RR=2,58) foram consideradas fatores de risco para fissuras palatinas.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Aromatic amines are environmental pollutants and represent one of the most important classes of industrial and natural chemicals. Some types of complex effluents containing these chemical species, mainly those originated from chemicals plants are not fully efficiently treated by conventional processes. In this work, the use of electrochemical technology through an electrolytic pilot scale flow reactor is considered for treatment of wastewater of a chemical industry manufacturer of antioxidant and anti-ozonant substances used in rubber. Experimental results showed that was possible to remove between 65% and 95% of apparent colour and chemical oxygen demand removal between 30 and 90% in 60 min of treatment, with energy consumption rate from 26 kWh m-3 to 31 kWh m-3. Absorbance, total organic carbon and toxicity analyses resulted in no formation of toxic by-products. The results suggest that the presented electrochemical process is a suitable method for treating this type of wastewater, mainly when pre-treated by aeration. Copyright © 2013 Inderscience Enterprises Ltd.